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Good Question: Do Treadmill Calorie Counts Work?

(WCCO) On the treadmill or the elliptical machine it's the one number on the display that can keep you moving: The calorie count. But how can a machine know how many calories we're burning?

"Well, it's an estimate," explained Beth Lewis, Ph.D., an Assistant Professor of Kinesiology at the University of Minnesota's College of Education and Human Development.

Lewis acknowledged that while she works out she consults a calorie counter on a watch that monitors her heartbeat, although, "I take it with a grain of salt," she said.

Each manufacturer uses a different formula to calculate the calories burned. Some, like Precor USA, say they created the formula in consultation with the American College of Sports Medicine.

Generally, those formulas include weight and age of the athlete, along with speed of the workout and incline or intensity level.

But, according to Lewis, there are many other factors that the machines do not factor in to their formulas.

"Genders often not, like I said body fat, your metabolism rate, how long you've been doing the machine, how efficient you are. Those are kind of the major variables that could play a role," she said.

According to WebMD.com, machine calorie counts tend to overestimate by 10 to 15 percent, at times they can overestimate by as much as 50 percent.

If the calorie readout indicates that you've burned 300 calories, it's possible you've burned closer to 265 calories. Either way, Lewis recommends that you don't take that number as an invitation to consume those calories as a reward for your workout.

"Saying I can eat an extra 300 calories tonight because I burned exactly 300 calories on the elliptical machine ... is not the most accurate thing," she explained.

"We've had a lot of participants [in our studies] tell us they like to use elliptical instead of the treadmill because it burns more calories. But because of inaccuracies, you really shouldn't base your workout on how many calories you burn," said Lewis.

However, Lewis said she doesn't believe the counts are useless. For some people they are a motivator.

"It can be helpful for looking at your progress," she added.

If you use the same machine every day, you want to try to increase the number of calories burned according to the display. To make that number increase, you'll pick up the intensity of your workout, which is a good thing.

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